Advanced Android Fragments, Tom Opgenorth
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This document summarizes advanced techniques for using fragments in Android applications. It discusses how fragments can retain their state across configuration changes using the retainInstance property. It also introduces two specific fragment types: DialogFragment for displaying modal dialogs, and PreferenceFragment for building settings screens. Code demos are provided for retaining fragment state and using DialogFragment and PreferenceFragment. The document emphasizes that fragments allow for modular, reusable UI components and help activities manage their state during configuration changes.
Advanced Android Fragments, Tom Opgenorth
- 1. Tom Opgenorth Developer / Writer Xamarin tom.opgenorth@xamarin.com Fragments - The Next Step (Advanced Fragments) @topgenorth
- 2. Topics to Look out For In this Session • Quick Review of Fragments • How Fragments can Help Their Host with State • Not ONE But TWO Fragments : DialogFragment PreferenceFragment
- 3. Review
- 4. What Do We Need to Remember About Fragments ? • Fragments Are Modular UI Think “mini-Activity” • Hosted in an Activity Statically - in Layout Dynamically - at Runtime • They inflate views (usually) • They have a lifecycle
- 6. • Runtime / Changes kill Activities State needs to be maintained • Custom objects to maintain state Subclass Java.Lang.Object Override OnRetainNonConfigurationInstance Check Activity.LastNonConfigurationInstance But these are DEPRECATED! Activity State Can Complex
- 7. - Leonardo da Vinci Simplicity is the Ultimate Sophistication
- 9. How Does this Impact the Fragment Lifecycle? Start OnInflate OnAttach OnCreate OnCreate View OnActivity Created OnStart OnResume OnPause OnStop OnDestroy View OnDestroy OnDetachRunning End
- 10. • Survives config changes! • Lightweight • Perfect for Background Process (Threads) Memory intensive Resources Sharing Data What Does This Mean - Exactly?
- 11. Demo 1
- 12. DialogFragment
- 13. Why Use DialogFragment? • Configuration changes are hard on dialogs Dialog Should Remain - but the Activity is destroyed • Customizable • “Managed Dialogs” - Old School
- 14. How Do I Use DialogFragments? • Subclass DialogFragment • Override one of the following methods: OnCreateDialog • A “proper” dialog will pop up OnCreateView • Inflate a View - then embed it • Modal, but not blocking
- 15. Demo 2
- 17. PreferenceFragment : Why Do I Care? • Preferred Way for Android 3.0 or Higher • Can Share Across Activities • Allows for Hierarchies PreferenceActivity Does Not
- 18. On A Tablet
- 19. On a Phone
- 21. Demo 3
- 22. What Were We Talking About Again? • Keep Fragments around with RetainInstance • DialogFragments Dialog or Embedded Modal but not Blocking! • PreferenceFragment
- 23. Q & A
- 24. THANK YOU